A known oil jet injects oil to a piston of an internal combustion engine (refer to patent document 1).
The internal combustion engine described in patent document 1 includes an oil jet passage, which is supplied with oil, oil jets, which are connected to the oil jet passage, and an oil jet valve, which regulates the amount of oil supplied from the oil jet passage to the oil jets. The internal combustion engine includes a socket that communicates the outside of the internal combustion engine with the oil jet passage. The oil jet valve is fitted into and fixed to the socket. Further, a flange is formed on the outer surface of the oil jet valve and shaped projecting outwardly. A seal member is held between the flange and the outer surface of the internal combustion engine. The seal member restricts the leakage of oil from the internal combustion engine through the gap between the oil jet valve and the socket of the engine.